Significance How does the brain perceive and interpret facial expressions? Substantial data indicate that there are specialized brain systems involved in the perception of faces. Disruption of these systems may be involved in diseases of social interaction such as autism and schizophrenia. Objectives This is a new program that is designed to evaluate the role of a brain region called the amygdala in the interpretation of facial expression. We will determine whether neurons in the amygdala specifically code for faces versus other complex objects and uniquely code for specific facial expressions Results Using state-of-the-art parallel recording technology, we will record the activity of up to 160 individual neurons while monkeys view faces and other complex objects on a video screen. The technology that will be employed is similar, though more sophisticated, to diagnostic techniques carried out in human epileptic patients. During the current year, preliminary experiments have been carried out to demonstrate the safety and effectiveness of the electrophysiological recording techniques. Efforts are currently underway to outfit a modern electrophysiological laboratory for these studies. Future Directions We will evaluate neuronal responses in awake, behaving monkeys who are viewing faces via a video screen. We will determine whether the ensemble coding of large groups of neurons is a better predictor of amygdala function than single neuronal activity. We will also carry out similar studies while animals are carrying out a discrimination task in which they will be asked to discriminate faces on the basis of expression, familiarity, gender, species and other social variables. KEYWORDS facial perception, social behavior, electrophysiology, amygdala